| Abbot's Priory | | | |
| a-bling | | | |
| a boon and a bane | | | |
| abound in one's own sense | | | |
| about time | | | |
| about to | | | |
| above and beyond | | | |
| above board | | | |
| above one's bend | | | |
| above one's huckleberry | | | |
| above par | | | |
| above the curve | | | |
| above the fray | | | |
| above the law | | | |
| above the salt | | | |
| above water | | | |
| a bridge too far | | | |
| absence makes the heart grow fonder | | | |
| abuse of distress | | | |
| accident of birth | | | |
| accident waiting to happen | | | |
| according to Cocker | | | |
| according to Gunter | | | |
| according to Hoyle | | | |
| ace in the hole | | | |
| ace up one's sleeve | | | |
| a cigar is just a cigar | | | |
| acknowledge the corn | | | |
| a cold day in July | | | |
| acquired taste | | | |
| across the board | | | |
| activist judge | | | |
| activist justice | | | |
| act of Congress | | | |
| act one's age | | | |
| act one's age, not one's shoe size | | | |
| act out | | | |
| act the hypocrite | | | |
| act up | | | |
| Adam's ale | | | |
| Adam Tiler | | | |
| a day late and a dollar short | | | |
| added value | | | |
| add fuel to the fire | | | |
| add insult to injury | | | |
| add oil | | | |
| add up | | | |
| a dime a dozen | | | |
| adorn oneself with borrowed plumes | | | |
| adrenaline rush | | | |
| adversarial collaboration | | | |
| Affair Partner | | | |
| afraid of one's own shadow | | | |
| after all | | | |
| after one's own heart | | | |
| after the fact | | | |
| after the Lord Mayor's show | | | |
| against all odds | | | |
| against the clock | | | |
| against the collar | | | |
| against the grain | | | |
| against the law | | | |
| against the run of play | | | |
| against the world | | | |
| age before beauty | | | |
| a good deal | | | |
| a great deal | | | |
| agree to disagree | | | |
| aha moment | | | |
| ahead of one's time | | | |
| ahead of the curve | | | |
| ahead of the game | | | |
| ahead of the pack | | | |
| a hundred and ten percent | | | |
| aim at | | | |
| ain't what it used to was | | | |
| airheaded | | | |
| airheadedness | | | |
| air one's dirty laundry in public | | | |
| air one's dirty linen in public | | | |
| air out | | | |
| air rage | | | |
| air sandwich | | | |
| alarums and excursions | | | |
| albatross around one's neck | | | |
| albatross round one's neck | | | |
| a little bird told me | | | |
| a little bit of bread and no cheese | | | |
| a little from column A, a little from column B | | | |
| a little of something goes a long way | | | |
| alive and kicking | | | |
| all along | | | |
| all and some | | | |
| all and sundry | | | |
| all-around | | | |
| all at once | | | |
| all bark and no bite | | | |
| all bedlam breaks loose | | | |
| all bets are off | | | |
| all dressed up and nowhere to go | | | |